B&C Speakers B&C 21SW152 21" Professional Neodymium Subwoofer 8 Ohm
Best box: 93.9 L bass reflex tuned to 39.7 Hz · F3 48.6 Hz
Open and tweak this box live ↗
Will it fit your requirements?
Check the B&C Speakers B&C 21SW152 21" Professional Neodymium Subwoofer 8 Ohm against your space and targets — instant, no sign-up.
Estimated retail 982.86 USD · Check price & availability ↗
Free, no sign-up to simulate · a free account saves your design
Comparable 21.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the B&C Speakers B&C 21SW152 21" Professional Neodymium Subwoofer 8 Ohm does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.
⚠️ Engineering Notice for Builders
- Port length (58.8 cm) exceeds a straight internal run; use an elbow bend, slotted vent or 3D folded duct to fit the enclosure.
Recommended Bass Reflex (Vented)
PORT NEEDS ELBOW / 3D| Net Box Volume (Vb) | 93.9 Liters |
| Tuning Frequency (Fb) | 39.7 Hz |
| F3 (-3 dB Cutoff) | 48.6 Hz |
| F6 / F10 Extension | 41.6 Hz / 34.5 Hz |
| Port Inner Diameter | Ø 21.6 cm |
| Port Physical Length | 58.8 cm |
| First Pipe Resonance | 293.0 Hz |
| Estimated MOL @ F3 | 128.7 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 43.5 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 72.7 Hz |
| F3 (-3 dB Cutoff) | 63.3 Hz |
| F6 / F10 Extension | 53.1 Hz / 43.1 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 32.0 Hz |
| Total Q (Qts) | 0.3 |
| Electrical Q (Qes) | 0.313 |
| Mechanical Q (Qms) | 7.0 |
| Equivalent Volume (Vas) | 198.2 Liters |
| Diaphragm Area (Sd) | 1680.0 cm² |
| DC Resistance (Re) | 6.0 Ω |
| Efficiency Bandwidth Product (EBP) | 102.1 |
| Linear Excursion (Xmax) | 15.0 mm |
| Thermal Power (Pe) | 4000.0 W |
| Nominal Diameter | 21.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for B&C Speakers B&C 21SW152 21" Professional Neodymium Subwoofer 8 Ohm?
Load Forge's calculated alignment puts B&C Speakers B&C 21SW152 21" Professional Neodymium Subwoofer 8 Ohm in a 93.9 liter vented enclosure tuned to 39.7 Hz, reaching an F3 cutoff of approximately 48.6 Hz.
Can B&C Speakers B&C 21SW152 21" Professional Neodymium Subwoofer 8 Ohm be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 43.5 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 63.3 Hz.
What port dimensions should be used for B&C Speakers B&C 21SW152 21" Professional Neodymium Subwoofer 8 Ohm to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 21.6 cm with a length of 58.8 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
Embed this design card on DIYAudio, AVSForum, Reddit, or Facebook. It shows the calculated F3, MOL (when the power rating is published) and box parameters.
Not sure if B&C 21SW152 21" Professional Neodymium Subwoofer 8 Ohm fits your physical space?
Don't force a driver into the wrong box. Use Bass Match to calculate which of 8,000+ catalog drivers delivers the highest SPL, lowest F3, and cleanest port air velocity for your exact trunk or room dimensions.
Run Bass Match for Your Space